1. Field of the Invention
This invention relates, in general, to photocopying apparatus and, more specifically, to scanning, with one or more cameras or scanners, simplex or duplex original documents traveling along one or more document paths.
2. Description of the Prior Art
An apparatus for optically scanning information, such as characters and graphics, illustrated on both sides of, for example, a sheet-shaped original is disclosed in U.S. Pat. No. 4,657,376. The apparatus includes a copying machine provided with an auto document feeder. With such a copying machine, an original is first set on an original table by the auto document feeder, then images on one side of the original are exposed and scanned by an optical unit. The original, after one side is scanned, is moved off the table by the document feeder and turned over, by a flipping unit mounted on the feeder, before the original is again set on the table for scanning image information on the other side of the original by the optical unit.
A problem with scanning original documents having images on both sides, hereinafter referred to as duplex scanning, with the above apparatus, is that such scanning is time consuming. It is time consuming because it requires one side of the original to be scanned and then flipped over before the other side can be scanned.
Further, the flipping unit used in the above apparatus is a complicated structure and jamming, of the original, in the flipping unit may occur as the original is flipped over.
Another apparatus used for duplex scanning of originals is disclosed in U.S. Pat. No. 4,908,719 where an original document is placed upon a conveyance path, constituting an auto document feeder and one side of the original, moving on the conveyance path, is scanned by a first optical unit located above the conveyance path and the other side of the moving original is scanned by a second optical unit disposed near the first optical unit, but located below the conveyance path.
The problem with this type of apparatus is that there is only one original document path and, therefore, during a simplex scanning operation only one optical system may be utilized during said operation, thereby rendering the other optical system redundant and of no assistance in completing the simplex scanning operation.
It is therefore a primary object of this invention to provide a reliable scanning apparatus that can scan images on both sides of an original in a single pass and in an expedient manner as well as scan images on only one side of an original at up to twice the through put rate of duplex scanning.